1. Field of the Invention
The present invention relates to a camera with a lens barrel mechanism which is driven by a motor only in one rotational direction, wherein rotational power of the motor in the other direction is used for driving another mechanism.
2. Background Arts
An instant camera takes a photograph on a sheet of instant film by exposing the instant film to an optical image of a subject formed through a taking lens. After the exposure, a film feed out mechanism is driven to feed out the exposed instant film. The film feed out mechanism is constituted of a claw mechanism and a pair of developing rollers, and is driven by a motor. The claw mechanism rakes the exposed instant film out of a film pack loaded in the instant camera and feeds it toward the developing rollers. Then, the developing rollers nip and feed out the instant film through a film exit of the instant camera. While the instant film is squeezing through the developing rollers, a pod containing a developing solution is broken and the developing solution is spread over the exposed instant film. Thereby, a latent picture photographed on the instant film is developed to be a visible positive picture.
Because the sheet size of the instant film is relatively large, the instant camera must have a sufficiently large room for loading the instant film, so it is difficult to make the instant camera compact in comparison with 35 mm cameras and APS cameras using IX 240 type film. In order to improve the portability of the instant camera, JPA 4-194829 discloses a collapsible instant camera wherein a lens board having a taking lens therein is mounted to a camera body through bellows so that the board may be folded onto a front wall of the camera body or protruded from the front wall. Because the collapsible instant camera is complicated in construction and needs a large number of parts, the production cost is high and the collapsible instant camera comes to be expensive.
It is desirable to introduce such a lens barrel in the instant camera that has been used in conventional compact cameras and is movable between a stowed position and at least a protruded position, but there are many problems to solve in practice. It is necessary to provide a second motor for driving the lens barrel besides the motor for the film feed out mechanism, since the movable lens barrel is driven by a motor in one direction to protrude or in a second or opposite direction to retract. In addition, where the taking lens is focused through a focusing mechanism that is driven by a different motor from that used for protrusion and retraction of the lens barrel, the instant camera must mount at least three motors. This is disadvantageous in view of compactness and cost.
To reduce the number of motors, JPZ 1869801 discloses a teaching to use rotational power of a motor in one direction for moving a lens barrel between a wide-angle position and a telephoto position, and rotational power in the other or opposite direction for driving another mechanism, e.g. a film advancing mechanism or a shutter charging mechanism. Also, JPA 9-236854 discloses a teaching to drive a film advancing, winding and rewinding mechanism by rotating a motor in one direction and drive another mechanism by rotating the motor in the other direction.
However, these prior arts just propose the teaching, and do not disclose any concrete solution for the achievement. For instance, there is no teaching how to move the lens barrel in opposite directions by rotating the motor in one direction, or how to focus the taking lens. Moreover, the torque necessary for driving one mechanism is usually different from that for another mechanism. When using the rotational power of the same motor for different mechanisms, the difference in the torque must be taken into consideration. Otherwise, the mechanism cannot operate stably and would rise a certain noise.
Meanwhile, many of instant cameras and inexpensive cameras use a taking lens with a relatively short focal length and a relatively small lens aperture, so that the taking lens covers a wider subject distance range within the depth of field. In those instant cameras or inexpensive cameras, the whole subject distance to cover is often divided into several zones, e.g. near, middle and far distance zones, and the taking lens is designed to be set to one of several focusing positions determined for the respective subject distance zones. It is well-known in the art to provide a manually operated zone focusing device instead of or in addition to an automatic focusing device. The zone focusing device allows the photographer to designate one of predetermined subject distance zones so as to focus the taking lens on the designated subject distance zone.
In the conventional zone focusing device, an operation member, such as a switching lever or dial, is connected to a focusing ring of the taking lens through an interconnection mechanism to switch over the focusing position by rotating the focusing ring through the operation member. So the operation member has been located in proximity to the taking lens to improve the space efficiency and simplify the interconnection mechanism. However, the conventional location of the operation member of the zone focusing device is not handy for the photographer, and also limit the layout of other camera elements.